Electrografting of a biodegradable layer as a primer adhesion coating onto a metallic stent: in vitro and in vivo evaluations.

Drug-eluting stents have been developed to reduce the risk of restenosis after angioplasty. To facilitate the adhesion of a poly(lactic acid) (PLA) overlayer loaded with rapamycin (20 wt%), a biodegradable macromonomer based on poly(lactic acid) (HEMA-PLA) was grafted onto the metallic stent by electrografting in a one-step reaction involving the immobilization of aryl diazonium onto the metal followed by an in situ surface electro-polymerization. The HEMA-PLA coating was chemically characterized. Mechanical performance during stent expansion was tested. Morphology examinations showed a strong adhesion of PLA topcoat in the presence of the electrografted layer. Biocompatibility and degradation of the coating were studied in vitro and in vivo in rabbit iliac arteries. These 28 days implantations resulted in a minimal inflammatory process with a partial degradation of the coating. These results suggest that this kind of anchoring of a biodegradable layer shows great potential for drug-eluting stents.